1. Field of the Invention
This invention relates to a data recording medium suitable for recording digital signals, for example, and a record/playback apparatus used for the data recording medium.
2. Description of the Related Art
Already known are multi-layered disks having a plurality of recording layers formed on a disk such that each layer is selectively read out under focus control of an optical pickup. For example, U.S. Pat. No. 5,263,011 discloses one of such multi-layered disks and a record and playback apparatus using the disk.
The technique on multi-layered disks by the above-identified document does not pay sufficient consideration for practical use, and it is still in the course of development. That is, no teaching is found about actual data writing and reading. In particular, no consideration is paid on recording and reproducing video data and/or audio data using compressed codes.
In a conventional CD (compact disk), for example, its recording track is formed to start from the inner side to the outer side of the disk. However, there has been no disclosure on how to form recording tracks on a multi-layered disk. Therefore, conventional techniques having been employed for single-layered disks involve many problems to be discussed henceforth, although they are employable in some limited cases.
In view of the situation, an object of the invention is to provide a data recording medium and a record/playback apparatus using the data recording medium.
According to the invention, there is provided a disk-shaped data recording medium, comprising:
at least a first and a second recording layers;
a first recording direction from the inner side to the outer side of the medium and a second recording direction from the outer side to the inner side of the medium being determined as directions for recording data;
one of the first and second recording directions being used as the recording direction of the first recording layer;
the other of the first and second recording directions being used as the recording direction of the second recording layer; and
each of the recording layers including a data area in which data has a sector structure, and each sector containing at least a layer number for identifying the first recording layer and the second recording layer.
On the data area of each layer, data has a sector structure, and each sector contains the number of total recording layers on the disk.
Recording areas are provided such that an inner guard area of a respective layer overlaps with an outer guard area of another layer, and TOC areas contain at least data for access to all layers and data for identifying respective layers.
The TOC area on the uppermost layer is provided in a location contiguous to the data area on the uppermost layer. The data area of each layer has a sector structure, and sector numbers of respective sectors are determined according to a numbering system enabling identification of at least the layer numbers.
A record/playback apparatus using the data recording medium according to the invention accesses the medium by utilizing the recording layers, TOC areas, sector structure, etc. of the medium.
The data recording medium according to the invention can be readily accessed because of the structure of the recording tracks. Therefore, the record/playback apparatus using the data recording medium according to the invention can easily access the medium at a high speed.
The above, and other, objects, features and advantage of the present invention will become readily apparent from the following detailed description thereof which is to be read in connection with the accompanying drawings.